feat!: `used_extensions` calls for both ops and signatures #2814

Job	Run time
Check for changes	20s
tests (Rust 1.75)	2m 55s
check	2m 0s
tests (Rust beta)	2m 17s
tests (Rust nightly, coverage)	4m 0s
Build benchmarks 🏋️	1m 57s
tests (Rust stable, all features)	2m 21s
tests (Rust stable, no features)	1m 21s
tests hugr-llvm	0s
Check standard extensions	4s
Required checks 🦀	1s
	17m 16s

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